Foundation Types Essay

2627 Words May 17th, 2016 11 Pages
Types of Foundation
The foundation is the base for the constructed building and as such is required to carry out several functions as follows:

0 The foundation should safely sustain and transmit to the ground the combined dead and imposed loads of the building without resulting in any settlement or other movement of the building or any adjoining works.

1 Foundations should be deep enough or be constructed in such a way as to avoid damage by the swelling, shrinkage or freezing of the subsoil.

2 The foundation should be capable of resisting attack by chemicals such as soluble salts or other deleterious materials present in the subsoil.
Choice of Foundation
The designer is required to choose the most appropriate type
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The idea of the trench fill foundation is to fill a narrow foundation trench , to a depth of 900 millimetres or more, with concrete and this is particularly useful in shrinkable clay soils in order to avoid problems caused by shrinkage and swelling as the seasons change. The foundation width is reduced to around 400-450millimetres with a depth to suit the particular site conditions. Those who support the use of trench fill foundations point to time savings and quick completion of groundwork, although this type of foundation is much more expensive in the cost of concrete.

The use of trench fill does require careful consideration of service entry, as in most cases services will have to be taken through the concrete foundation by providing holes or ducts. The positioning of service holes or ducts will require accurate setting out to in order to avoid expensive mistakes.

Trench fill foundation with substructure brickwork. Finished ground level will be the height of the drain cap.

Trench fill foundation with substructure brickwork. Finished ground level will be the height of the drain cap.

Raft Foundation
A raft foundation is simply a foundation which covers the whole area of the building and will normally be used in soils deemed to have a poor bearing capacity. They are normally used in ground which is soft such as filled sites liable to subsidence, for example in mining areas or

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